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The Measurement of Spinal Cord Tissue pH Using a Diffusible, Lipid‐Soluble, pH‐Sensitive Fluorescent Indicator
Author(s) -
Delheimer Steven C.,
Anderson Robert E.,
Sundt Thoralf M.
Publication year - 1980
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1980.tb11232.x
Subject(s) - spinal cord , normocapnia , chemistry , hypercapnia , hypocapnia , ph indicator , respiratory system , anesthesia , anatomy , biology , medicine , neuroscience
Spinal cord tissue pH was measured in cats at normocapnia, hypocapnia, hypercapnia and death from anoxia using a pH‐sensitive fluorescent indicator (umbelliferone) with both molecular and ionic fluorophors. A ratio analysis of the indicator's calibrated 450 nm fluorescent tissue clearance curves from 340 and 370 nm excitation permitted direct in vivo tissue pH determinations. Fifteen animals were divided into three equal groups according to different arterial carbon dioxide tensions (P a co 2 ):five animals at P a co 2 20, five animals P a co 2 40 and five animals P a co 2 60 torr. Spinal cord tissue pH varied linearly with arterial pH, but within narrower limits. These values (arterial versus cord pH) were: 7.46 versus 7.15; 7.21, 7.09; and 7.04, 7.00. At death from hypoxemia the arterial pH fell to 6.99 and spinal cord to 6.67. The clearance curves of umbelliferone in spinal cord varied according to P a co 2 and appeared to reflect spinal cord blood flow.